1. Research on fundamental of the basic mechanical characteristics of foam-filled corrugate sandwich panel

Our team has come up with the third generation of new composite structures, namely the foam lattice composite structures, which is based on the former research on traditional foam and lattice lightweight porous structure. Particularly, basic mechanical properties like compress, shear and bend abilities of it is investigated through experiment, calculation and analysis approach. We found that foam-filled corrugate sandwich panel is good in compress ability and energy absorption ability, thus it has a prospect. 

1.1    Research on compression property outside the surface

By means of experiment, numerical simulation, we have got the compression property outside the surface of foam-filled corrugate sandwich panel, the influence of foam alluminium fill on the strength and energy absorption properties of corrugate sandwich panel, and explained the principle of its property strengthening mechanism. Filled with foam can enrich the destructive ways. Foam-filled corrugate sandwich panel is as good as square opening honeycomb in compression strength and energy absorption.

Figure 1: process on foam-filled corrugate sandwich panel

Figure 2: foam-filled corrugate sandwich panel: (a) A single element; (b) glued interface; (c) sample on a hollow corrugate sandwich panel; (d) sample on foam-filled corrugate sandwich panel

Figure 3: Quasi-static compression stress-strain curve of foam alluminium, hollow corrugate panel and foam-filled corrugate sandwich panel

Figure 4: Destruction images of the samples under different strain: (a) hollow corrugate panel (b) foam alluminium filled corrugate panel (c) foam alluminium

Figure 5: Formation of plastic hinge of the foam-filled corrugate sandwich panel

Figure 6: Destruction mode of foam-filled corrugate sandwich panel structure under outside compression

Figure 7: Transformation principle of foam-filled corrugate sandwich panel

Figure 8: Comparison of outside compression property for foam-filled corrugate sandwich panel: (a)outside compression strength (b)energy absorption strength

Figure 9: Comparison of outside compression property for foam-filled corrugate sandwich panel： (a)outside compression strength，(b)energy absorption strength

Figure 10: Bending failure mode for sandwich beams：(a)foam-filled corrugate sandwich beam，(b)hollow corrugate sandwich beam

2、Research on the basic mechanical properties for metal foam

2.1 Reverse construction of 3D FEA model for close cell aluminum

Based on the CT scanned information of close cell foam aluminum, we have reconstructed two kinds of relative-density close cell foam aluminum 3D model and generated the hexahedron element by means of reverse engineering(see figure 11). Uniaxial compression simulation is performed on 3D close cell foam aluminum FEA model and the parameters of close cell foam aluminum wall material are output by experimental data.

Figure 11: Process of close cell foam aluminum model sample: (a)X-ray faultage photograph for 3D point cloud model，(b)get rid of the perforated wall model by Boolean operation，(c)3D point cloud model for foam aluminum cell hole，(d)cell hole detachment，(e)paving fitting for each closed cell hole，(f)fill each closed cell hole，(g)get rid of each cell hole by Boolean operation，(h)3D microcosmic model，(i)mesh generation by hexahedron element

2.2 triaxial compression behavior and yielding surface for close cell foam aluminum

We have achieved the numerical simulation for the mechanical properties of the blue zone under stress by changing the load boundary of the 3D microscope FEA model of the close cell foam aluminum, as shown in figure 1. By defining the proportionality coefficient of the load path, we performed three boundary conditions, say, side-way coupled uniaxial compression, hydrostatic compression and equal proportion compression, we have achieved the large deformation compression process under 11 different load paths, and got the range of the  proportionality coefficient which can give support for research on the compression constitutive relation of close cell foam aluminum.

  Figure 12: stress state for close cell foam aluminum

Figure 13: verification for the yielding surface of volume strengthen constitutive relation

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